The prebiotic potential of Australian honeys Nural Cokcetin, Shona Blair & Patricia Conway The University of New South Wales Sydney, Australia
Introduction Gut bacteria significantly impacts host health & disease Prebiotics alter bacterial composition of gut Honey has prebiotic potential
Gut bacteria 10 14 bacteria (100,000 billion!!) > 500 different types Stomach 10 2 to 10 3 Lactobacilli Streptococci Lactobacilli Duodenum Jejunum < 10 4-5 Enterobacteria Enterococcus faecalis Bacteroides Bifidobacteria Peptococcus Peptostreptococcus Ruminococcus Clostridia Lactobacilli Ileum Colon 10 3 to 10 7 10 9 to 10 12
Gut bacteria 10 14 bacteria > 500 different types Lactobacilli Streptococci Lactobacilli Stomach Duodenum Jejunum 10 2 to 10 3 < 10 4-5 Enterobacteria Enterococcus faecalis Bacteroides Bifidobacteria Peptococcus Peptostreptococcus Ruminococcus Clostridia Lactobacilli Ileum Colon 10 3 to 10 7 10 9 to 10 12
Why are gut bacteria important? Help modulate immune system Contribute to metabolism of the host Contribute to energy harvest from food Some gut bacteria associated with bowel diseases, allergy & obesity Need a balance of good and bad bacteria
Good vs. Bad bacteria Good Health promoting: Eg Bifidobacteria and Lactobacilli Inhibit growth of harmful bacteria Stimulate immune functions Improve digestion and absorption of essential nutrients Bad Exert harmful effects: Eg Clostridia and Bacteroides Involved in diarrhoea, infections and liver damage Can produce carcinogens Cause intestinal putrefaction Synthesise vitamins
Changes in gut bacteria Sommer and Backhed (2013). Nature Reviews Microbiology, 11:227-238.
The gut system Stomach Duodenum Jejunum - Food digested and absorbed in small intestine - Simple sugars absorbed in small intestine i.e. fructose, glucose, sucrose Ileum Colon - Good bowel bacteria get left-overs need complex sugars Honey contains simple AND complex sugars
What is a prebiotic? Complex sugars that: are not digested in upper gut reach colon intact used as a food source by good gut bacteria Colon Sources of prebiotics: breast milk some root crops (e.g. chicory) Differ from probiotics- live bacteria
Probiotics vs. prebiotics Live bacteria Food for gut bacteria
Honey Super saturated sugar solution Mainly fructose (36-50%) and glucose (28-36%) (simple sugars) Oligosaccharide (~1-4%) (complex sugars) Exact composition: highly variable dependant on floral source Australian floral honeys unique Therapeutic properties Antioxidant, immunostimulatory, wound healing, antimicrobial, prebiotic Not all honeys are the same
Is Australian honey a good prebiotic? Can good bacteria use honey to grow? Can honey help good bacteria outcompete bad bacteria?
Stage 1 Can good bacteria use honey to grow? (tested 17 honeys) l counts Chemical analysis
Prebiotic effect of Australian honeys on the growth of good bacteria Honeys 1 2 3 4 5
Prebiotic effect of Australian honeys on the growth of good bacteria Honeys 1 2 3 4 5
Prebiotic effect of Australian honeys on the growth of good bacteria Honeys 1 2 3 4 5
Stage 2 Can honey help good bacteria outcompete bad bacteria? (17 + 22 honeys) l counts Chemical analysis Phase 1: Simulate gut conditions Phase 2: Use complex sugars in tests
Prebiotic Index (PI) Measures prebiotic capacity Generates score of prebiotic effect Bifidobacteria & Lactobacilli (+)ve value Bacteroides & Clostridia (-)ve value
Prebiotic index values for Australian honeys 450 400 350 300 250 200 150 100 50 0 PI index Inulin Sucrose No sugar Honey 2 Honey 5 Honey 7 Honey 9 Honey 14
All Australian honeys support growth of good bacteria (lactobacilli)
All Australian honeys suppress growth of bad bacteria (clostridia)
Prebiotic index values for Australian honeys
Prebiotic index and oligosaccharides
Chemical analysis of beneficial end products
What do these results mean? Australian honeys: have prebiotic activity oligosaccharides deliver health benefits could be an effective functional food ingredient Each honey could provide different health benefits Prebiotic, nutritional, therapeutic
Acknowledgements RIRDC funded project UNSW Lab Dr Lai Tran Associate Professor Torsten Thomas Dr Meera Esvaran Rosie Stern